Speed and Accuracy of CFD: Achieving Both Successfully ANSYS UK S.A.Silvester

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1 Speed and Accuracy of CFD: Achieving Both Successfully ANSYS UK S.A.Silvester 2010 ANSYS, Inc. All rights reserved. 1 ANSYS, Inc. Proprietary

2 Content ANSYS CFD Introduction ANSYS, the company Simulation Driven Product Development Five steps in a CFD simulation Simulations available in ANSYS CFD Performance measures of ANSYS CFD Accuracy Speed Robustness Ease of use Optimisation Illustration 2010 ANSYS, Inc. All rights reserved. 2 ANSYS the Company ANSYS, Inc. Proprietary

3 ANSYS, the company ANSYS design, develops, markets and globally supports a range of CAE simulation software Paramterization Meshing A suite of multi-purpose software technologies for Fluid Dynamics Thermal Structural Mechanics Implicit Structural Fluid Explicit Dynamics Electromagnetics CAD Import Emag Workflow Multiphysics Selection of specialised tools Specialist thermal/flow for electronics Postprocessing 2010 ANSYS, Inc. All rights reserved. 3 SDPD ANSYS, Inc. Proprietary

4 Simulation Driven Product Development Instead of just using engineering simulation for verification or trouble-shooting, many companies are turning to Simulation Driven Product Development (SDPD) Design, simulate, optimise Physically test only the best candidates The benefits of SDPD Better performing products Shorter development times Reduced development costs 10X 100X Productivity Gain Customer needs Business drivers Technology trends 2010 ANSYS, Inc. All rights reserved. 4 5 Steps ANSYS, Inc. Proprietary

5 Five Steps in a CFD Simulation Your CAD or ANSYS Geometry tool CFD Meshing CFD Physics set-up CFD Solving CFD Postprocessing ANSYS CFD is a multi-purpose CFD system Current version R13.0 Widely used in industry and academia 2010 ANSYS, Inc. All rights reserved. 5 Simulation Types ANSYS, Inc. Proprietary

6 Simulations available in ANSYS CFD ANSYS CFD - addressing your current and future CFD challenges Transient or steady-state Laminar and turbulent flows SST, Transition, DES/LES/SAS Heat transfer Convection, conduction and radiation Buoyant flows Incompressible / compressible Multi-component flows, Multi-phase e.g. Bubbly flow, water droplets... Real gas modelling Filters/Porous regions Reactions and combustion Moving geometry and mesh Rotating machinery (multiple frames of reference) Solution-based adaptive remeshing 1-way and 2-way Fluid-Structure Interaction 2010 ANSYS, Inc. All rights reserved. 6 Accuracy ANSYS, Inc. Proprietary

7 Performance measures of ANSYS CFD - Accuracy Accuracy How can we be sure that the numerical models we have implemented give the correct results? Comprehensive suite of solver models, allowing the simulations of Real world geometries Challenging physics, many types of flow Bubbly, swirling, high speed, buoyancy driven... Every single one of the numerous available models needs to be tested ANSYS, Inc. All rights reserved. 7 Test Cases ANSYS, Inc. Proprietary

8 Performance measures of ANSYS CFD - Accuracy Every new numerical model gets tested against experimental data Currently 125 new test cases, variations on each one Tested on all supported architectures 2010 ANSYS, Inc. All rights reserved. 8 Recondensation ANSYS, Inc. Proprietary

9 Bartolomej et al. Test case with Recondensation Geometry Pipe flow; axial symmetry Inner radius of pipe R = mm Total pipe length L T = 1.4 m Heated section length L H = 1.0 m Flow parameters Upward directed water flow p in = 6.89 MPa Parameter Investigation L T L H R Outlet Adiabatic Wall Symmetry Axis q wall Heated Wall Mass G in Liquid T in Wall heat flux q wall G in,t in, p in Inlet 2010 ANSYS, Inc. All rights reserved. 9 Results ANSYS, Inc. Proprietary

10 Bartolomej et al. Test case with Recondensation Distribution of water temperature and steam volume fraction 2010 ANSYS, Inc. All rights reserved. 10 Comparison ANSYS, Inc. Proprietary

11 Bartolomej et al. Test case with Recondensation Comparison of cross-sectional averaged steam volume fraction to experimental data 2010 ANSYS, Inc. All rights reserved ANSYS, Inc. Proprietary

12 Performance measures of ANSYS CFD - Accuracy Every new numerical model gets tested against experimental data Currently 125 new test cases, variations on each one Tested on all supported architectures All existing models get validated using a series of test data Currently around 800 cases get regression tested EVERY night Tested on all supported architectures 2010 ANSYS, Inc. All rights reserved. 12 Back Step ANSYS, Inc. Proprietary

13 Backward facing step Structured Grids (11,793, 46,383 and 183,963 nodes) Fully Developed Turbulent Flow at Inlet Experiments by Driver and Seegmiller (1985) Reynolds Number Re H = H= [m] 4 x H 35 x H 8 x H Inlet H Flow Separation Outlet 2010 ANSYS, Inc. All rights reserved. 13 Cavity ANSYS, Inc. Proprietary

14 Natural Convection in a Tall Cavity Structured Grids (20,000, 80,000 and 320,000 nodes) Heated and cooled Wall at ΔT = 19.6 K Experiments by Betts & Bokhari (2000) Cooled Wall Tw = 293 K Heated Wall Tw = K H W 2010 ANSYS, Inc. All rights reserved. 14 Customer ANSYS, Inc. Proprietary

15 Performance measures of ANSYS CFD - Accuracy Every new numerical model gets tested against experimental data Currently 125 new test cases, variations on each one Tested on all supported architectures All existing models get validated using a series of test date Currently around 800 cases get regression tested EVERY night Tested on all supported architectures Customers report back their own experiences 2010 ANSYS, Inc. All rights reserved. 15 Customer Validation ANSYS, Inc. Proprietary

16 Customer Validation 2010 ANSYS, Inc. All rights reserved. 16 World Expertise ANSYS, Inc. Proprietary

17 Performance measures of ANSYS CFD - Accuracy Every new numerical model gets tested against experimental data Currently 125 new test cases, variations on each one Tested on all supported architectures All existing models get validated using a series of test date Currently around 800 cases get regression tested EVERY night Tested on all supported architectures Customers report back their own experiences All validation, testing and the worlds largest pool of technical experts allows compilation of a comprehensive set of CFD Best Practices 2010 ANSYS, Inc. All rights reserved. 17 Speed ANSYS, Inc. Proprietary

18 Performance measures of ANSYS CFD - Speed Speed How quickly will I get an accurate solution? The actual runtimes are based on several different factors mesh size, problem complexity, machine specifications, solver efficiency... However, runtimes can be accelerated considerably using ANSYS HPC 2010 ANSYS, Inc. All rights reserved. 18 HPC ANSYS, Inc. Proprietary

19 Performance measures of ANSYS CFD - Speed ANSYS HPC allows you to Run simulations over multiple processors Local or distributed Mixed machine architecture Development ethos All physics combinations MUST be able to be run in parallel Constantly testing new architectures Develop the software to perform on latest hardware 2010 ANSYS, Inc. All rights reserved. 19 Packs ANSYS, Inc. Proprietary

20 Performance measures of ANSYS CFD - Speed ANSYS HPC Packs enable high-fidelity insight Each simulation consumes one or more packs Parallel enabled increases quickly with added packs Single solution for all physics and any level of fidelity Flexibility as your HPC resources grow Reallocate Packs, as resources allow Parallel Enabled (Cores) Packs per Simulation ANSYS, Inc. All rights reserved. 20 Parallel Test Cases ANSYS, Inc. Proprietary

21 Performance measures of ANSYS CFD - Speed Parallel test cases Problem Description Name of Definition file Type Number of nodes Turbulence model Case 1 perf_airfoil_r12.def External Aero KE Case 2 perf_airliftreactor_r 12.def Other physical model Compressible, Total Energy Multiphase KE Inhomogeneous Case 3 perf_indycar_r12.def External Aero KE Incompressible Case 4 perf_internal_r12.def Multiphase KE Thermal Energy Case 5 Case 6 perf_lemanscar_r12. def perf_pump_r12.def External Aero KE Thermal Energy Rotating Machine KE Frozen Rotor 2010 ANSYS, Inc. All rights reserved. 21 Case 1 Aerofoil ANSYS, Inc. Proprietary

22 Speed Up Test Case 1 - Airfoil Mesh Count nodes Performence Linear Number of Cores 2010 ANSYS, Inc. All rights reserved. 22 Case 2 Reactor ANSYS, Inc. Proprietary

23 Speed Up Test Case 2 - Air Lift Reactor Mesh Count nodes Performence Linear Number of Cores 2010 ANSYS, Inc. All rights reserved. 23 Case 3 Indy ANSYS, Inc. Proprietary

24 Speed Up Test Case 3 - Indy Car Mesh Count nodes Performence Linear Number of Cores 2010 ANSYS, Inc. All rights reserved. 24 Case 4 Internal ANSYS, Inc. Proprietary

25 Speed Up Test Case 4 - Internal Mesh Count nodes Performence Linear Number of Cores 2010 ANSYS, Inc. All rights reserved. 25 Case 5 Lemans ANSYS, Inc. Proprietary

26 Speed Up Test Case 5 - LeMans 35 Mesh Count nodes 30 Performence Linear Number of Cores 2010 ANSYS, Inc. All rights reserved. 26 Case 6 Pump ANSYS, Inc. Proprietary

27 Speed Up Test Case 6 - Pump Mesh Count nodes Performence Linear Number of Cores 2010 ANSYS, Inc. All rights reserved. 27 Robustness ANSYS, Inc. Proprietary

28 Performance measures of ANSYS CFD - Robustness Robustness How do we make sure the software works considering a wide source of: Geometry Physics Experience etc... Various options and defaults have been implemented throughout the entire software ANSYS, Inc. All rights reserved. 28 Templates ANSYS, Inc. Proprietary

29 Performance measures of ANSYS CFD - Robustness Workbench allows you to choose an analysis type Appropriate defaults are automatically set 2010 ANSYS, Inc. All rights reserved rd CAD ANSYS, Inc. Proprietary

30 Performance measures of ANSYS CFD Robustness ANSYS utilises 3 rd party CAD No import/export issues Bidirectional parametric link Parameters from CAD to Workbench Parameters from Workbench to CAD 2010 ANSYS, Inc. All rights reserved. 30 Auto Setup ANSYS, Inc. Proprietary

31 Performance measures of ANSYS CFD - Robustness ANSYS CFD requires that you input information pertinent to the simulation Choice of fluid Boundary conditions etc... On most cases, having input the information you know, you simply run the simulation Robust solver settings Poor quality mesh treatment Compressive scheme 2010 ANSYS, Inc. All rights reserved. 31 Param Expose ANSYS, Inc. Proprietary

32 Performance measures of ANSYS CFD - Robustness Pervasive parameters Geometric of Physical input parameter Output response parameters Batch Processing One click multiple simulations Design Exploration and Optimisation Several optimisation methods Create response surfaces Parameter sensitivity Response surface Spider chart Local sensitivity 2010 ANSYS, Inc. All rights reserved. 33 Manifold ANSYS, Inc. Proprietary

33 Optimisation - Simple Case Study Simple manifold Objective - Same flow rate (within 2%) at the vents Can alter the 3 inlet pipe diameters Inlet Pipe Diameters Vent 4 Vent 3 Vent 2 Vent ANSYS, Inc. All rights reserved. 34 Manifold ANSYS, Inc. Proprietary x

34 Optimisation - Simple Case Study Run Diameter 1 Diameter 2 Diameter 3 Vent 1 Vent 2 Vent 3 Vent % 22% 22% 25% % 27% 24% 42% % 19% 18% 18% % 23% 26% 4% % 19% 20% 41% % 4% 4% 40% % 37% 37% 12% 2010 ANSYS, Inc. All rights reserved. 35 Optimisation Tools ANSYS, Inc. Proprietary

35 Optimisation - Simple Case Study Optimisation tools provides suitable candidates Diameter 1 Diameter 2 Diameter 3 Vent 1 Vent 2 Vent 3 Vent 4 There is now a maximum of 2% between the four outlets Diameter 1 Diameter 2 Diameter 3 Vent 1 Vent 2 Vent 3 Vent 4 DX % 25% 25% 26% Re-Run % 25% 24% 26% 2010 ANSYS, Inc. All rights reserved. 36 Ease ANSYS, Inc. Proprietary

36 Performance measures of ANSYS CFD Ease of Use Ease of use What is Accuracy, Speed and Robustness if you can t use it? ANSYS CFD tackles ease of use in numerous ways ANSYS, Inc. All rights reserved. 37 Systems ANSYS, Inc. Proprietary

37 Performance measures of ANSYS CFD Ease of Use ANSYS Workbench simply selects the analysis type Appropriate steps created for the simulation 2010 ANSYS, Inc. All rights reserved. 38 Consistent GUI ANSYS, Inc. Proprietary

38 Performance measures of ANSYS CFD Ease of Use There is a consistent look and feel where ever data is being entered Data is passed seamlessly Geometry Meshing Problem Setup Post Processing 2010 ANSYS, Inc. All rights reserved. 39 Geometry ANSYS, Inc. Proprietary

39 Performance measures of ANSYS CFD Ease of Use Geometry Import CAD Direct from 3 rd party CAD tool Automatically generate fluid volume De-feature & repair One click symmetry tool Full suite of solid modelling tools 2010 ANSYS, Inc. All rights reserved. 40 Meshing ANSYS, Inc. Proprietary

40 Performance measures of ANSYS CFD Ease of Use Meshing Default mesh setting based on geometry and physics choice Automatic near wall meshing Inspect Mesh Check quality 2010 ANSYS, Inc. All rights reserved. 41 Problem Setup ANSYS, Inc. Proprietary

41 Performance measures of ANSYS CFD Ease of Use Problem Setup Setup wizard lets you set up simulations with confidence Can generate your own panels to tailor your set-up 2010 ANSYS, Inc. All rights reserved. 42 Custom ANSYS, Inc. Proprietary

42 Performance measures of ANSYS CFD Ease of Use 2010 ANSYS, Inc. All rights reserved. 43 Post ANSYS, Inc. Proprietary

43 Performance measures of ANSYS CFD Ease of Use Post Processing Full Suite of tools: Contour Plots Vector Plots Charts Tables Reports Etc... One click to re-run with new parameters!! 2010 ANSYS, Inc. All rights reserved. 44 DX Example ANSYS, Inc. Proprietary

44 Summary Providing industry-leading accuracy & speed of CFD Time-tested, sophisticated physical models Thoroughly verified and validated against tests Continuous performance advancements in solver numerics Powerful and scalable HPC Meeting highest Quality Assurance standards Long-standing experience and expertise supporting world s largest customer base in CFD We continue to focus on shortening the overall time to a reliable solution 2010 ANSYS, Inc. All rights reserved. 47 End ANSYS, Inc. Proprietary